As we enter the height of this hot, humid summer, more and more of us will be heading to the beach. But it's not just more swimmers. There are also more sharks than ever near our shores. Tonight after one man nearly dies in the jaws of a great white, a new warning from the California city, a 60-day fishing prohibition, while they investigate the latest attack. Here's ABC's nick Watts. Get out of the water! Shark! Reporter: This shaky video shot from the pier captures the terrifying moment a shark thrashing, then Steve Robles screams. His morning swim turned into a nightmare. Shark attack on a busy beach, July fourth weekend. You saw it coming at you. It made a real fast, sharp left turn and lunged right at my chest. You could just hear everything crunch. Reporter: People on land realized what just happened. Oh ! Reporter: Fellow swimmers and surfers got Robles ashore on this bloody surfboard. And I was screaming and screaming. And crying and screaming. And I was holding on to my cut. Reporter: The horrifying wounds left behind. The shark, a seven or eight-foot juvenile, was mad. Right here! Reporter: He'd been hit by a fisherman on the pier when Steve, a long-distance swimmer, got in the way. I grabbed its nose with this hand. And tried to pry it off of my chest. I was staring at the shark eyeball to eyeball, literally like right here. It was the most frightening thing I ever -- anyone could ever experience. Reporter: He punched the shark in the nose a bit bit once more and disappeared. What was going through your mind? I didn't want to die. Just -- I was scared. I was -- I was panicked. Don't worry, don't worry, it's over. Reporter: At Manhattan beach sharks are spotted nearly every day by audacious paddle boarders. This is the first time one has attacked here. New studies show the great white population is increasing on both coasts. Conservation efforts are working. In fact, the great white population in American waters is up 42% since 1997. And so are sightings. Last week, a 12-footer was spotted off a cape cod vacation spot. Days earlier an 18-footer spotted by fishermen just a few mile away. Shark attacks are still extremely rare. There were just 47 in American waters last year, only one fatality. Throughout the world it's actually very rare, considering how many people enter the water, to how many times the great whites actually swim by. Very, very, very rare. Reporter: Your odds of getting killed by a shark at the beach are 200 million to 1. Sharks, we are not on their menu. Reporter: How best to avoid being the next Steve Robles? The golden rule -- don't be an idiot. Do not an tag news a shark. You don't bother them, chances are they will not bother you. But more and more it seems people are taking chances with sharks. Just to get a glimpse or even a close-up encounter. Youtube is filled with amateur videos like this. . He's checking me out. Whoo! Oh my god, right under the board. Reporter: Paddle boarders chasing sharks with cam rath right here at Manhattan beach where Robles just got bit. We saw a big, dark shape. Yep, here he is. Reporter: Surfers armed with go pros risking their safety for video proof of their adventures. That's a beautiful shark, wow. Reporter: There's even an annual event from discovery: Shark week fueling our fascinati fascination. Here's a young great white in one of their upcoming specials. Similar to the one Robles encountered. Juveniles, but they're going for these birds that are on the surface. Reporter: It's believed these juveniles come to the surface for hunting practice. Shark mania as it were has spawned a new crop of shark junkies drawn to the danger and thrill. Sean Harrington is trying to create a viral video to promote his clothing line and he admits it went a bit wrong. I seen the shark coming for me, I just threw the bird cage behind my legs and pretty much just saved me from probably grabbing my legs. I've got to thank the bird cage, really. Reporter: Check out this Florida teen who hitched a ride on a whale shark last summer. I decided that, you know what, I should maybe try and swim with him. Because I might not be able to do it ever again. You're Crazy. Reporter: This is a nantucket fisherman who grabbed a 200-pound sand shark in the surf. &Hc it seems wild, running into the water and grabbing a shark by its tail. Reporter: There's a whole new industry, shark tourism, worth $300 million a year and growing. I went cage driving with great whites in Africa a couple of years ago -- but even that's old hat these days. Matt Gutman went diving with tiger shark in the Ba ham mays wearing nothing but a wet suit. What to do if on that rare occasion you're in fear of being ashacked by a shark? First up, if you see one and he's not lunging at you, swim calmly to shore. They go under surfers, we see them jump out of the water, nothing really happens. Reporter: If the shark attacks fight back. Punch it on the nose like Steve reasons Robles did. It was instinctive. It has all its electrical pulses in its nose. That will whack out the shark. Unfortunately, the teeth are close to the nose. Reporter: If it bites, gouge at its gills andize. You have to keep a cool mind. If you can, that's the best way to do it. Reporter: Back to Steve Robles, he was just in the worst place at the worst time. Shark! Get out of the water! Reporter: Juvenile white dozen not attack humans. This apparently only the second recorded case. And Robles doesn't blame the shark. He blames the fisher machine. It was that guy that was agitating that shark. That caused all this. Reporter: Many beachgoers this weekend agree with Robles. Sounds like out of fear he attacked a person because he was scared for his life. Putting surfers' lives in danger shouldn't be allowed. I think it should be banned. Reporter: Some eyewitnesses say they've seen fishermen purposefully attracting sharks. Fishermen like to have the thrill of catching the fish. The big fish. The fighting of the fish. Reporter: Which takes us back to the golden rule. Don't antagonize them and chances are they won't attack you or anyone else. I just got really lucky. I'm getting a second chance. Reporter: For "Nightline," nick watt, ABC news, Manhattan beach, California.

This transcript has been automatically generated and may not be 100% accurate.

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